Intel Corp. (INTC) recently showed off a demo called "Thunderbolt Technology Update", which is basically a second-generation Thunderbolt solution. The next generation Thunderbolt is capable of piping "4K video file transfer and display simultaneously."

Marco Armanet, co-founder of Tumblr and founder of Instapaper, writes in his blog:

This could enable the first generation of desktop Retina displays: it wouldn’t surprise me if the first standalone Retina display was a 23” panel with exactly 4K resolution (3840?×?2160), run logically as 1920?×?1080 (1080p) at 2X, and driven by upgraded Thunderbolt ports in the next generation of MacBook Pros and Mac Pros.

If Apple's 4K monitors follow a similar release trajectory to its 2.5K monitors, it could see the tech trickle-down to a premium variant of its MacBook Pro laptops sometime around 2015. The current ~2.5K MacBook Pro Retina units are rough 220 ppi; a 4K unit would be around 350 ppi.

The prospect of a 350 ppi MacBook Pro would be impressive, but not out of the ballpark. Currently, the Galaxy S IV by Samsung Electronics Comp., Ltd. (KSC:005930) packs a 440 ppi, 1080p, 5-inch display. Scaling up super-dense displays is difficult, but Apple and Google have shown that it can be done.

The company also retails a $999 USD Thunderbolt Display for use with its laptops and desktops. That display packs a "2560-by-1440 LED-backlit display, a FaceTime HD camera, high-quality audio, three USB 2.0 ports, a FireWire 800 port, a Gigabit Ethernet port, and a Thunderbolt port for daisy-chaining additional high-performance devices."

quote: Ethernet has had cables which deliver those speeds for years, and they do not have overpriced chips. In addition, the Ethernet cables are not limited to 3 meters.

Ethernet also is not designed to carry an electrical current along the entire span of the cable, besides the usual 0s and 1s. Power over Ethernet (POE) isn't very popular outside the surveillance systems market, and a large majority of routers and switches are not equipped to handle POE.

TB cables are limited to 3 meters because of electrical current losses i.e. physics, and the need to run bus-powered devices without additional external power.

10GbE cables might have been around for "years", but they were fiber. Only recently have there been some copper-based 10GbE ethernet cables.

IIRC, thunderbolt was initially supposed to carry data over fiber and power over copper. Cost/complexity made Intel/Apple settle on copper for the first iteration of 10Gb Thunderbolt. But the plan was always to scale up to 100Gb, and move data to fiber.

As for why they couldn't have just used 10GbE copper or 10GbE fiber cables for the first gen thunderbolt- I don't know. But I suspect it has something to do with wanting their future combined data fiber/power copper cables and chipsets to be backwards compatible with today's cables.